On Wed, Jun 5, 2024 at 1:49 PM Ravi Bangoria <ravi.bangoria@xxxxxxx> wrote:
>
> SEV-ES and thus SNP guest mandates LBR Virtualization to be _always_ ON.
> Although commit b7e4be0a224f ("KVM: SEV-ES: Delegate LBR virtualization
> to the processor") did the correct change for SEV-ES guests, it missed
> the SNP. Fix it.
>
> Reported-by: Srikanth Aithal <sraithal@xxxxxxx>
> Fixes: b7e4be0a224f ("KVM: SEV-ES: Delegate LBR virtualization to the processor")
> Signed-off-by: Ravi Bangoria <ravi.bangoria@xxxxxxx>
> ---
> - SNP support was not present while I prepared the original patches and
> that lead to this confusion. Sorry about that.
No problem, this is a semantic conflict and your original patches will
go in 6.10. Applied to kvm/next.
Paolo
> arch/x86/kvm/svm/sev.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index 7d401f8a3001..57291525e084 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -2395,6 +2395,14 @@ static int snp_launch_update_vmsa(struct kvm *kvm, struct kvm_sev_cmd *argp)
> }
>
> svm->vcpu.arch.guest_state_protected = true;
> + /*
> + * SEV-ES (and thus SNP) guest mandates LBR Virtualization to
> + * be _always_ ON. Enable it only after setting
> + * guest_state_protected because KVM_SET_MSRS allows dynamic
> + * toggling of LBRV (for performance reason) on write access to
> + * MSR_IA32_DEBUGCTLMSR when guest_state_protected is not set.
> + */
> + svm_enable_lbrv(vcpu);
> }
>
> return 0;
> --
> 2.45.1
>
